Probing Photothermal Effects on Optically Trapped Gold Nanorods by Simultaneous Plasmon Spectroscopy and Brownian Dynamics Analysis
Journal article, 2017

Plasmonic gold nanorods are prime candidates for a variety of biomedical, spectroscopy, data storage, and sensing applications. It was recently shown that gold nanorods optically trapped by a focused circularly polarized laser beam can function as extremely efficient nanoscopic rotary motors. The system holds promise for-applications ranging from nanofluidic flow control and nanorobotics to biomolecular actuation and analysis. However, to fully exploit this potential, one needs to be able to control and understand heating effects associated with laser trapping. We investigated photothermal heating of individual rotating gold nanorods by simultaneously probing their localized surface plasmon resonance spectrum and rotational Brownian dynamics over extended periods of time. The data reveal an extremely slow nanoparticle reshaping process, involving migration of the order of a few hundred atoms per minute, for moderate laser powers and a trapping wavelength close to plasmon resonance. The plasmon spectroscopy and Brownian analysis allows for separate temperature estimates based on the refractive index and the viscosity of the water surrounding a trapped nanorod. We show that both measurements yield similar effective temperatures, which correspond to the actual temperature at a distance of the order 10-15 nm from the particle surface. Our results shed light on photothermal processes on the nanoscale and will be useful in evaluating the applicability and performance of nanorod motors and optically heated nanoparticles for a variety of applications.

photothermal effects

Brownian dynamics

gold nanorod

thermal reshaping

nanomotors

optical tweezers

Author

Daniel Andrén

Chalmers, Physics, Bionanophotonics

Lei Shao

Chalmers, Physics, Bionanophotonics

Nils Odebo Länk

Chalmers, Physics, Bionanophotonics

Srdjan Acimovic

Chalmers, Physics, Bionanophotonics

Peter Johansson

Chalmers, Physics, Bionanophotonics

Mikael Käll

Chalmers, Physics, Bionanophotonics

ACS Nano

1936-0851 (ISSN) 1936-086X (eISSN)

Vol. 11 10 10053-10061

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Subject Categories

Atom and Molecular Physics and Optics

DOI

10.1021/acsnano.7b04302

PubMed

28872830

More information

Created

11/22/2017